This invention pertains to a composite material, and more particularly to a liquid impervious composite material having a cloth-like texture on one side thereof and a method for making the same.
Various types of garments are presently available for absorbing human discharge. Examples of these garments include baby diapers, training pants, feminine care products, incontinent garments, and the like. The general structure of these garments include a liquid pervious bodyside liner, an absorbent batt, and a liquid impervious outer cover for containing discharged fluids or solid matter.
One suitable liquid impervious material for use as the outer cover is a thermoplastic film. Although functional as a liquid impervious barrier, it has a characteristic which can be considered undesirable, or even unacceptable, to the wearer. That characteristic is the film's plastic appearance and particularly the plastic feel or texture. In the case of diapers, it may be the mother who objects to the plastic appearance and feel of the diaper against her baby. In the case of training pants for a child or incontinent garments for adults, it is the wearer who will object to the plastic appearance and feel.
Various solutions to this undesirable characteristic of plastic appearance or feel have been pursued. One such attempt is to manufacture the outer cover of a thermoplastic film or composite with a cloth-like texture on the outer surface. One method includes uniformly applying a thin adhesive coating on the surface of a thin film, and then depositing loose filaments on the thin, uniform adhesive layer. Thereafter, the layer of fibers and film may be passed between two nip rolls to insure good adherence between the fibers and film. Although resulting in an article having some cloth-like appearance and texture, the article has less loft and softness than desired, which is probably due to the fact that the fibers are compactly adhered to the film by the layer of adhesive therebetween. In other words, because of the uniform and continuous adhesive layer, there may be too many fibers partially or completely adhered to the film, thereby tending to cause the fibers to lose some of their loft and softness.
Another method, somewhat similar to the above, includes blowing fiber webs onto a thermoplastic film, and then fuse-bonding the layer of fibers and film together by, for example, passing them between heated nip rolls or through some other type of fusion device, such as a heater. The heat causes the surface of the film to become soft and tacky, thereby providing the mechanism for adhering the fibers to the film. Because the total surface of the thermoplastic film provides the necessary adhesive characteristic, the fiber side of the article has less loft and softness than desired.
In another method, loose fibers are blown onto a web or thermoplastic film, and thereafter a liquid binding agent is applied to the fibers and penetrates through the layer of fibers to the film, thereby causing adherence between the fibers and film. If desired, the article can then be passed through a heating or drying device. The resulting article has less loft and softness than those earlier described since the liquid binding agent completely penetrates the layer of fibers resulting in adherence not only between the fibers and film, but also between adjacent fibers due to the running or spreading of the liquid binding agent.
Still another method includes providing a pre-bonded layer of nonwoven fibers, and then meltblowing a plastic onto the pre-bonded fiber layer. The adhesion is provided by the softened and tacky meltblown plastic fibers. Again, the resulting article has less than desired loft and softness due to the meltblowing process and also due to the layer of fibers having been pre-bonded prior to the meltblowing step.
Similar to the just-described method, a pre-bonded layer or web of fibers may have a plastic film coated or extruded thereon. As with the above method, the extruded film adheres not only to the points of density in the fiber layer where the fibers are pre-bonded, but also to points of the fibers between these points of pre-bond density.
Another problem associated with the lack of desired loft and softness occurs when providing a portion of the article with an elasticized opening, such as a waist or leg opening. Upon relaxing the elastic after it has been attached to the article in its stretched state, it gathers that portion of the article to which it is attached. It is naturally desirable not only to provide good elasticity about the opening, but also a pleasing appearance by the gathered portion of the article. Because of the lack of desired loft and softness of the above-described cloth-like articles, they generally do not uniformly gather into the desired pleasing appearance. This is due in part by the slight stiffness of the article caused by the methods of adhering the loose fibers to the film, as earlier described above.
Thus, the need exists for an improved cloth-like, liquid impervious article that has better loft and softness characteristics, and which presents a pleasing gathered appearance upon being elasticized.